The present invention relates generally to motors, and more particularly, to a differential epicyclic power train employing two or more motors coupled to a differential epicyclic gear train that sums the motor speeds such that the output speed of the power train is a linear function of the motor speeds.
Prior art related to the present invention includes a direct reduction gear coupled to a motor, with or without a multi-speed transmission, that provides a means for varying the output speed and maintaining the output speed of the motor within a limited speed range. Another alternative prior art approach is a variable speed high power motor, operating over a wide speed range. Both known approaches suffer from a loss of efficiency. The former direct reduction gear approach has an efficiency loss due to excessive frictional losses associated with the transmission, while the latter variable speed motor approach has an efficiency loss due to operation in low efficiency regions.
Consequently, it is an objective of the present invention to provide for a motor arrangement wherein an epicyclic gear train sums inputs from two or more motors such that the output speed of the combination is a linear function of the input speeds.